When your on Berlin level (Or the place where you set off the cannons, and be Benjamin Franklin as a character can't remember the name sorry) you will obviously notice 2 skating ranks below 2 buildings. Ride up and crash through the window on your left. You should see a fat kid with sunglasses and a stick. Press circle near him and he'll "try" to harness a "lightsabor". Crash through the window on the right and you'll see a man standing with a lamb, goat or other animal.

Go to the cheat codes menu in the main menu options and enter birdman. Then go to secret skaters when your choosing your skater and he should be there.

Go to the cheat code menu in the options in the main menu and enter tightrope.

To get easy hi-scores in Free-Skate/Hi-score mode, skate toward a quarter Pipe (make sure you don't skate at an angle,not even 10 degrees!) and quickly
Press triangle at the peak.

Keep the arrow steady for 10 seconds,and press X.
Repeat this process without tripping/falling and you'll have a hi score in no time.